The present invention relates generally to the securing of tubes in a passage of a support, and more particularly to a method of affording such securing and to an apparatus for carrying out the method.
Tubes must frequently be secured in a passage of a support, for instance a tube plate or the like. This is often required in heat exchangers, and very frequently is now demanded in the construction of reactors. In the latter instance, in particular, the region of the tube where the latter is mechanically deformed so as to be retained in the passage formed in the tube plate of the reactor, is subjected to very high stresses. Various ways of securing the tube by deforming it outwardly within the passage, have become known, such as the so-called Pilgrim-step method which is also known as the Mannesmann method, a quick-step rolling method, or an automatically operating rolling method. None of these, however, have been found to be satisfactory because in all instances it was observed that at least over a period of time fissures will develop in the material of the tube which has been expanded, such fissures being the result of stresses that have been set up during the expansion which is caused by rolling of the tube material. The fissures are found particularly at the juncture between the rolled portion of the tube and the non-rolled portion thereof. This is not tolerable, because the weakening of the material which is caused by the presence of these fissures can lead to a deterioration of the material strength to such an extent that the material will finally fail, with consequences which at the very least are disadvantageous in terms of down time, and which in the case of reactors can be downright disastrous.